1. Field of the Invention
The present invention relates to a beam sampler made of a highly transparent substrate. A three-dimensional diffracting relief is etched directly onto the substrate to extract from a light beam being sampled at least one pair of low power beam samples.
2. Brief Description of the Prior Art
As the applications of high-power lasers increase, the need for a complete monitoring of laser beam characteristics becomes increasingly crucial. Those skilled in the art will appreciate that beam-sampling devices represent one of the key technologies in such beam monitoring.
Obviously, real-time operation and pulsed-laser compatibility require a real sampler as opposed to a time sampler, since the latter provides only average values.
A prior art light beam sampler comprises a substrate of transparent light-propagating material defining two opposite and substantially parallel planar surfaces through which the laser beam to be sampled propagates in a direction generally perpendicular to these surfaces. A coating of resinous substance is applied to the one of the two planar surfaces through which the laser beam leaves the substrate. A diffracting relief is recorded on the outer face of the resinous coating to extract from the laser beam at least one pair of low power beam samples. The characteristics of the beam samples conform with those of the sampled laser beam whereby these samples can be analyzed to determine the different parameters of the laser beam.
Although the above described prior art sampler is capable of sustaining laser beams at low power levels, the resinous coating substance deteriorates rapidly when submitted to high power laser beams. Also, the performance of the resinous coating is affected by the environmental conditions such as the temperature and humidity. A further drawback is the limited spectral region in which the resinous coating substance operates satisfactorily.